I think the color of his shirt kinda what's ruining it. In some pictures, the pose doesn't seem natural. I like both the black & white photos. As you can see from the BW photos, it has better contrast. His skin is really light and that orange shirt doesn't go well with it. I think when he has the full smile, it seems force or not natural. #8, his smile looks natural. Some people just don't have a full natural smile, so if they don't find a smile that looks natural on them. The colors and exposure are fine. Try to find more interesting location so the background doesn't look boring. My 2 cents, I'm sure other expert will have more to say.